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Molecular Survey of Concrete Biofilm Microbial Communities
Citation:
Iker, B., R. P. REVETTA, J. Garcia, J. Sullivan, J. Weast, D. J. MURRAY, AND J. W. SANTO-DOMINGO. Molecular Survey of Concrete Biofilm Microbial Communities. Presented at American Society for Microbiology 110th General Meeting, San Diego, CA, May 23 - 27, 2010.
Impact/Purpose:
To inform the public.
Description:
Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA gene sequence analysis. A total of 18 samples were collected from manholes, a combined sewer overflow (CSO), and top (crown) and bottom sections of a corroded sewer pipe. Clone libraries were developed using eubacterial primers and sequences analyzed to determine the phylogenetic affiliation of each of the clones. A total of 2457 clones were analyzed in this study, representing 655, 456, 178, and 207 operational taxonomic units (OTU) for each of the aforementioned sample types (i.e., at 98% identity). In general, Protoeobacteria were among the most dominant groups in the samples studied with alpha, beta, gamma, and delta representing on average 15%, 22%, 11%, and 4% of the clone libraries. However, the results showed that beta proteobacteria (47%) sequences were more abundant in the pipe crown clones than any of the other concrete surfaces. Similarly, Bacteroidetes (34%) was found in the bottom pipe clones, which is in agreement with the greater exposure to fecal waste. Clones closely related to that of the genera Thiobacillus, Thiomonas, Acidothiobacillus, Halothiobacillus, Thiothrix, Acidophilium, Desulfovibrio, Desulfobacter, and Desulfuromonas were found in the libraries. These bacterial groups have previously been isolated from biofilms implicated in concrete corrosion. Interestingly, only four sequences closely related to Sphingopyxis spp. were shared among the different clone libraries, suggesting that these communities are very diverse and differ in overall composition of most abundant members. The results of this study suggest that at the 16S rRNA level, the concrete biofilms hold very different phylogenetic community structures, and that it might be necessary to focus on particular functional groups to better understand the dynamics of concrete corrosion.
